PURPOSE: Previous studies have suggested that supine gastroesophageal reflux may be reduced by abstinence from eating prior to bed time. The present study was designed to directly assess the importance of dietary indiscretion and nocturnal supine reflux. METHODS: Nineteen subjects with abnormal supine acid contact time (supine acid contact time > 5%) on ambulatory pH monitoring prior to study entry completed the protocol. The study was a 2-blinded randomized cross-over trial. Subjects underwent over night pH monitoring with supine acid contact time determination (10 p.m. to 7 a.m.) on the Clinical Research Unit. For both sessions, subjects received a refluxogenic evening meal at 6 p.m. (938 kilocalories, 50% fat) prior to retiring at 10 p.m. In addition, subjects were fasted after the evening meal for one of the sessions while during the other session they received a 9 p.m. bed time snack (500 kilocalories, 50% fat). RESULTS: Mean supine acid contact time for the bed time snack session was 9.5% versus 2.8% for the no snack session (P=0.015). Of the 10 subjects with abnormal supine reflux (supine acid contact time > 3%) on the snack session, eight had greater than or equal to 50% decrease in the supine acid contact time in the absence of a bed time snack. CONCLUSIONS: Dietary modification is an effective means for reducing nocturnal supine reflux. Supine reflux can be reduced by more than 70% by absence from eating for four hours before bed time. SIGNIFICANCE: The significance of these findings is that much supine acid contact may be preventable by not eating prior to bed time. Supine acid reflux is particularly injurious to the esophagus because of the effects of gravity, decreased swallowing during sleep, and decreased saliva production during sleep. FUTURE PLANS: We are currently in the process of designing studies to determine the impact of this finding on patients with supine reflux as a whole.